Reversible pump



April 8, 1958 E. s. WITCHGER V REVERSIBLE PUMP 2 Sheets-Sheet 1 FiledMay 51, 1955 INVENTOR. 5. W/TCf/GER April 8, 1958 E. s. WITCHGER2,829,602

REVERSIBLE PUMP Filed May 51, 1955 2 Sheets-Sheet 2 INVENTOR. 3.VV/TCHGER United States Patent REVERSIBLE PUMP Eugene S. Witchger,Grosse Pointe, Mich., assignor to Eaton Manufacturing Company,Cleveland, Uhio, a corporation of Ohio Application May 31, 1955, SerialNo. 511,934 9 Claims. (Cl. 103-426) This invention relates to pumps andmore particularly to unidirectional flow, reversible pumps.

Broadly the present invention comprehends the provision of a rotary typepump having cooperable, eccentric, inner and outer rotors and being soconstructed as to be automatically operative to provide unidirectionalflow from intake to discharge ports irrespective of the direction ofrotation of the pump rotors.

In the past, reversible, unidirectional flow pumps of the type shown inU. S. Patent No. 2,373,368 to Eugene S. Witchger have been devised andoperated with much success. It has, however, been discovered that suchpumps can be rendered more responsive, that is, capable of eifecting amore immediate adaptation to rotation reversals, by schemes forproviding an increased engagement between rotor members. the subjectmatter of U. S. Patent No. 2,458,678 to George F. Bunte. Prior artarrangements for improving response, however, are unduly complicated andemploy a number of parts requiring fine, detailed machining operationsincreasing the cost thereof.

It is accordingly an object of the present invention to provide animproved, more responsive, reversible, unidirectional flow gear pump.

It is a further object of the present invention to provide simplified,effective, economical means for enhancing the response of reversible,unidirectional flow, gear pumps.

It is a further object of this invention to provide a pump havingpumping means comprising an outer rotor and a pair of inner rotorswithin and eccentric to the outer rotor, automatically operative toadapt to reverse rotation of the rotors to provide unidirectionalpumping.

It is a further object of the present invention to provide a reversible,unidirectional flow, gear pump and a pumping chamber with the peripheralwalls comprising 3 circular sections having displaced centers ofcurvature and a bipartite inner rotor with means urging the separationof the parts thereof to accomplish a quick shift of the outer rotor fromengagement with one circular chamber section to another in response toreversal of rotation of one of the inner rotors.

Other and further objects and advantages will become manifest from thefollowing detailed description taken with the accompanying drawings inwhich:

Fig. 1 shows a cross-sectional side view of the pump of the presentinvention,

Fig. 2 shows an end view with of the pump in Fig. 1,

Fig. 3 shows an end view of shown in Fig. l; and

Fig. 4 shows in crosssectional side view a pump incorporatingmodifications of the present invention.

According to the present invention a gear type rotary pump is providedhaving a pumping chamber recessed in a pump housing with a generallycircular peripheral wall but being comprised of 3 circular sections,each of a third of a circle in circumference. Two of the porthe endcover removed,

the pump cover plate One such improvement is,

tions have equal radii of curvature but with displaced centers ofcurvature and within the pumping chamber is an outer rotor with acircular outer periphery of the same radius of curvature as the twomentioned portions and shiftable for selective engagement with eitherthereof. A pair of inner rotors eccentric to the outer rotor and havingouter teeth engageable With the teeth on the inner surface of the outerrotor are provided. The inner rotors are axially adjacent each other andlike the outer rotor have a combined axial extent substantially equal tothe depth of the recess. Each inner rotor has one fewer teeth than theouter rotor and the teeth have, therefore, diametrically opposed fullmesh and open mesh positions and intermediate positions in contactingrelation with each other.

Provision is made for urging the axial separation of the inner rotors toforce at least one of them against the pump housing. Additionalprovision is made for driving one of the inner rotors so as to impart arotary motion thereto and to effect a rotary motion of the outer rotorwhose teeth are in engagement with the inner rotors. As a consequencethe second inner rotor is driven by virtue of its engagement with theouter rotor.

The force tending to separate the inner rotor members causes the driveninner rotor member to rub against an axial limit enclosing the pumpingchamber and to cause the rotor member to drag and be displaced angularlyby the amount permitted by the clearance between inner and outer rotors.Under these conditions: the shift of the outer rotor from contact withone circumferential portion of the pumping chamber to another iseffected quickly and easily upon a reversal of rotation of the driveninner rotor, since the lagging rotor enables a rocking action of theouter rotor at its point of contact with the outer rotor.

Referring now to the drawings for a more detailed description of thepresent invention 10 represents generally the pump housing having ahollow, narrow elongated portion 12 for receiving a drive shaft 14 and awide portion 16 provided with a recessed pumping chamber 18 and aplurality of axial holes 19 for receiving bolts 21 to secure anappropriate cover plate 22 to the housing to cover the chamber duringoperation. Holes: 20 are provided as means to attach the pump housing toa suitable pump carrying member.

Within recess 18 an outer rotor 24 having a smooth circular outercircumference and a geared inner circumference is provided and withinrotor 24 are a pair of inner rotors 26 and 28 having geared outerperipheries in engagement with the gears of rotor 24. Each of the innerrotors has 12 teeth or one fewer than the number of teeth on rotor 24,viz., 13. Rotor 26 is affixed to shaft 14 for rotation therewith by aplate 23 having an axial key portion 25 and a radial portion 29 affixedto shaft 14. Rotor 28 is not afiixed to any other component of thesystem. Each of rotors 26 and 28 is recessed along adjacent portions toprovide room for a Bellville type or washer spring 27 for urging theseparation of the rotors.

The pumping chamber 18 has an outer wall with 3 sections, eachcomprising an arc of a circle. The first section extends from A to B,the second section from B to C and the third section from C to A, asseen most clearly in Fig. 2. The curvature of each of the first 2 namedsections is the same as that of rotor 24 so as to provide even mutualengagement with the rotor under certain conditions as set forthhereinbelow and the extent of each is approximately /3 of a circle. Thecurvature of the third section is not critical, it being necessary onlyto provide sufficient space for rotor 24 to shift unimpeded fromengagement with either of sections AL-B and B-C to the other thereof;The centers of curvature of each of asaaeoa the sections A---B and B-Care displaced from each other as shown at D and B, respectively, and aredisplaced equally on opposite sides of the center F of rotor 26. Thedistance between the center F and each of the centers D and E is equalto the eccentricity of the rotors 24 and 26 so that when the outer rotor24 is lying in contact with the surface AB or in contact with thesurface B-C, it is rotatably supported in the proper eccentric relationwith respect to the inner rotor 26 in both cases. The surfaces A-B andB-C not only serve as bearing surfaces for the outer rotor 24, but alsoserve as stop surfaces which limit bodily shiftable movement of theother in the plane of rotation in the chamber 1% as will readilybeappreciated.

It will be understood that in a pump having pumping elements of the typedescribed the positions of full mesh and open mesh of the teeth of thepumping element will be in a plane including the axis of rotation of theouter rotor. In the construction shown and as viewed in the drawing thisplane is a horizontal plane perpendicular to the plane of the paperincluding the point P, and the axis of the shaft 14, and including thepoints D and E. Consequently when the outer rotor 24 is in a position asshown in Fig. 2 Where its center coincides with point D, the point offull mesh between the teeth of the rotors will be at the right-hand sideof the pump in horizontal alignment with the axis of the shaft 14 andthe position of open mesh will be at a diametrically opposite point onthe left-hand side of the shaft 14. Conversely when the rotors are in aposition so that the axis of outer rotor 24 coincides with the point Eunder which conditions the above relation of parts will be reversed,that is, the point of full mesh will lie on the left-hand side of theshaft 14 and the point of open mesh will be diametrically opposite fromthe axis of the shaft 14 therefrom.

The pumping action in a pump of the type described is obtained throughpumping chambers whichare opened up, or increase in volume, as the teethmove from full mesh position in the direction of rotation of the pumpingelement to open mesh position, and through contraction or closing ofsuch pumping chambers as the teeth of the two rotors move from open meshposition in the direction of rotation of the rotors to full meshposition. Thus in the construction shown where the outer rotor 24- is inthe position indicated in Fig. 2 and the rotors are turning in thedirection of the arrow identifying such direction in that figure, thefull mesh position is at the right-hand side of the center F of theshaft 1 and in horizontal alignment therewith and the pumping chambersformed between the teeth of the rotors 24 and 26 and increasing involume lie below the axis of the shaft 14 While those decreasing involume lie above the axis of such shaft.

Similarly when the outer rotor 24 is in a position that its centercoincides Wit point B, rotor 24 will engage surface B-C of chamber 13and the point of full mesh is in horizontal alignment with the axis P onthe left hand side of the shaft 14 while the open mesh position is onthe diametrically opposite side of the shaft. However, it will beappreciated that when the rotors are turning in a direction reverse tothat indicated by the arrow in Fig. 2 the expanding chambers formedbetween the teeth of the rotor will lie below the axis of the shaft 1while the contracting chambers formed between the teeth still lie abovethe axis F of the shaft in other words, irrespective of the relativepositions of the rotors 2d and 26 the expanding pumping chambers formedbetween the teeth of the rotors always lie below the axis of the shaft14 and the contracting pumping chambers formed between such teeth alwayslie above the axis of the shaft 14. Consequently an inlet port 3b formedin the cover plate 22 is always in open communication with the expandingpump ing chambers formed between the teeth of the rotor, and a dischargeport is always in open communication with the contracting pumpingchamber formed between the teeth of the rotor. inlet port 30communicates with a chamber 31 formed in the cover plate 22 anddischarge port 32 communicates with a chamber 33 also formed in thecover plate. Chambers 31 and 33 are shown in cross-sectional contourmore clearly in Fig. 3 of the drawings.

The outer rotor 24 is automatically shifted to a position to engagesurface B-C of the pumping chamber upon reversal of rotation of innerrotors 26 and 28. According to a feature of the invention the responseof the pump, that is, the shift of rotor 24 from contact with surface ABto surface B-C is expedited by the action of spring 27 applied betweenrotors 26 and 28. Spring 27 forces rotor 28 against the pocket or bottomof pumping chamber 18 and equally and oppositely tends to force rotor 25against end cover plate 22. Because of the friction between rotor 23against the pocket a drag tending to retard the rotation of rotor 28 isapplied thereto and this rotor lags behind inner rotor 26 by the amountof clearance between inner and outer rotors. This mismatch enables therotor set to adapt for reverse rotation thereof immediately since thedriven inner rotor 28 tends to retard the rotation of outer rotor 24 andinduces a rocking action thereof to shift to an adjacent stoppingsurface and operate in a manner explained hereinabove.

In accordance with a modification of the invention, a simplification iseffected as shown in Fig. 4 by the provision of an interchange of rotors26 and 28 and a ball drive of the driven rotor 26. As shown in Fig; 4 aball 49 is located between rotor 26 and shaft 14 in the adjacentrecessed portions of each. Spring 27 is located similarly as in Figs. 1and 2 and performs a similar function. It is to be understood that dragon driven inner rotor 28 is effected by friction between rotor 28 andcover plate 22.

In a further modification of the present invention as shown also in Fig.4, the separation of rotors 26 and 28 is accomplished by the axial biasof diametrically opposed springs 50 and 51 to effect the desired drag tofacilitate a quick response of the pump in a manner similar to thatalready explained hereinabove with respect to other embodiments of theinvention.

While the present invention has been described with reference to certainspecific embodiments thereof, it is readily obvious to those skilled inthe art to which the invention appertains that many changes andmodifications may be made therein and that the end drag on the driveninner rotor maybe obtained in many different ways without deviating fromthe spirit or scope of the invention. It is, accordingly, intended thatit be limited as set forth in the appended claims.

What I claim is:

1. A pump structure comprising a housing having a. chamber therein,pumping means in said chamber comprising an outer rotor member and apair of inner rotor members eccentric to said outer rotor member, saidouter rotor having interengaging teeth with each of said inner rotors,means for supporting and driving a first of said inner rotors about anaxis fixed with respect to said housing, a second of said inner rotorsbeing freely floating with respect to said first inner rotor drivingmeans and said outer rotor, said outer rotor being bodily shiftable insaid mentioned chamber in a plane perpendicular to said axis between tworelatively different positions, said housing having inlet and outletport means opening into said pumping chamber, said ports maintaining thesame pumping action irrespective of which of said positions said outerrotor is in, and means cooperative with said inner rotors to facilitatea quick response of said. pump to rotation reversals of the first ofsaid rotors.

2. A pump structure according to claim 1 wherein said last mentionedmeans comprises spring means interposed between said inner rotors urgingthe axial separation of said inner rotors and thrust absorbing surfacesaxially adjacent each of said inner rotors with the second of said innerrotors being brought into engagement with its associated thrustabsorbing surface.

3. A pump structure comprising a housing having a chamber therein,pumping means in said chamber comprising an outer rotor member and apair of inner rotor members eccentric to said outer rotor member, saidouter rotor having interengaging teeth with each of said inner rotors,means for supporting and driving a first of said inner rotors about anaxis fixed with respect to said housing, a second of said inner rotorsbeing supported on and rotatable with respect to said first inner rotordriving and supporting means, said outer rotor being bodily shiftable insaid mentioned chamber in a plane perpendicular to said axis between tworelatively different positions, said housing having inlet and outletport means opening into said pumping chamber, said ports maintaining thesame pumping action irrespective of which of said positions said outerrotor is in, means cooperative with said inner rotors for urging theseparation thereof and a pair of thrust absorbing surfaces, forming aportion of the housing and outwardly disposed axial end of each adjacentone of said inner rotors.

4, A pump structure comprising a housing having a chamber therein,pumping means in said chamber com prising an outer rotor and a pair ofaxially adjacent inner rotors eccentric to said outer rotor, said outerrotor having interengaging teeth with each of said inner rotors, theadjacent surfaces of said inner rotors being recessed, means located insaid recesses for axially biasing said rotors away from each other,axially opposed thrust absorbing surfaces adjacent axially oppositesurfaces of said inner rotors, means for supporting and rotating a firstof said inner rotors about an axis fixed with respect to said housing,the second of said inner rotors being supported and rotatable about saidaxis and being driven by said outer rotor whereby said second innerrotor lags angularly behind said first inner rotor due to the clearancebetween outer and inner rotors, said outer rotor being bodily shiftablein said mentioned chamber in a plane perpendicular to said axis betweentwo relatively difierent positions, said housing having inlet and outletport means opening into said pumping chamber, said ports maintaining thesame pumping action irrespective of which of said positions said outerrotor is in whereby the drag of said second rotor facilitates a rapidresponse of said pump.

5. A pump according to claim 4 wherein the recessed surfaces of saidinner rotors are annular in shape.

6. A pump structure according to claim 5 wherein said means located inthe recesses of said inner rotors is a washer spring.

7. A pump structure comprising a housing having a chamber therein and acover plate covering said chamber, pumping means in said chambercomprising an outer rotor member and a pair of adjacent inner rotormembers eccentric to said outer rotor member, said outer rotor memberhaving interengaging teeth with each of said inner rotors, said innerrotors and said outer rotor having an axial extent equal to the axialextent of said chamber, means for supporting and driving a first innerrotor adjacent said cover plate about an axis fixed with respect to saidhousing, the second of said inner rotors being driven only by said outerrotor, said outer rotor being bodily shiftable in said mentioned chamberin a plane perpendicular to said axis between two relatively ditferentpositions, said housing having inlet and outlet port means opening intosaid pumping chamber, said ports maintaining the same pumping actionirrespective of which of said positions said outer rotor is in, meanscooperative with said inner rotors for urging the separation thereof,said cover plate and the axial end of said chamber absorbing the thrustof said inner rotors whereby the second inner rotor is caused to drag tofacilitate a rapid shift of said outer rotor from one of said positionsto the other to accommodate reversals of said driving means.

8. A pump structure accrding ltO claim 3 wherein said means urging theseparation of said inner rotors comprises a pair of springsdiametrically, oppositely disposed between said inner rotors.

9. A pump structure according to claim 8 wherein the means for drivingone of said inner rotors comprises a shaft rotatable about said axis,and additionally comprising a pair of adjacent opposed recesses in saidshaft and the first of said inner rotors and a rigid ball located insaid recesses to afford drive between said shaft and said rotor byvirtue of shear resistance of said ball.

References Cited in the file of this patent UNITED STATES PATENTS1,334,906 Keith Mar. 23, 1920 1,964,330 Pitt June 26, 1934 2,373,368Witchger Apr. 10, 1945 2,458,678 Bunte Ian. 11, 1949 2,492,073 Taylor uDec. 20, 1949

